RESUMO
For realistic interaction models, which include both molecular attraction and repulsion (e.g., Lennard-Jones, modified Lennard-Jones, Morse, and square-well potentials), the asymptotic behavior of the virial expansions for pressure and density in powers of activity has been studied taking power terms of high orders into account on the basis of the known finite-order irreducible integrals as well as the recent approximations of infinite irreducible series. Even in the divergence region (at subcritical temperatures), this behavior stays thermodynamically adequate (in contrast to the behavior of the virial equation of state with the same set of irreducible integrals) and corresponds to the beginning of the first-order phase transition: the divergence yields the jump (discontinuity) in density at constant pressure and chemical potential. In general, it provides a statistical explanation of the condensation phenomenon, but for liquid or solid states, the physically proper description (which can turn the infinite discontinuity into a finite jump of density) still needs further study of high-order cluster integrals and, especially, their real dependence on the system volume (density).
RESUMO
On the basis of the recently established "hole-particle" symmetry of the lattice-gas Hamiltonian, the high-density equation of state has been derived in a form of pressure and density expansions in powers of activity. This equation is proposed as an alternative and complementary to the previously obtained pressure expansion in powers of density. For the well-known Lee-Yang lattice-gas model (a two-dimensional square lattice with a square-well interaction potential), the power coefficients (i.e., cluster and irreducible cluster integrals) up to the seventh order have been evaluated as accurate functions of temperature. The convergence of the expansions in powers of both density and activity to the exact Lee-Yang solution is investigated.
RESUMO
Based on the fundamental Bogolyubov chain of equations, a model relating the structural and thermophysical properties of the nonequilibrium liquid systems under irradiation in stationary state is introduced. The obtained results suggest that the thermophysical properties of the liquid systems under irradiation are defined by the "effective temperature" that can be calculated from the perturbed momentum distribution functions of the systems. It is shown that the structural changes in the liquid systems under irradiation are caused by the changes in the coefficients of the Maxwell distribution function due to the momentum exchange between the active particles and the particles forming the liquid. To confirm the theoretical predictions, a qualitative comparison of the model with the existing experimental data on irradiation influence on the surface tension coefficients of liquids is performed.
RESUMO
In this manuscript a theoretical model describing the influence of the heavy ion radiotherapy on the liquid matter in the human body is suggested. Based on the fundamental equations of Bogoliubov chain the effective temperatures in the case of constant particles fluent are found in the context of single component model. An existence of such temperatures allows the use of equilibrium thermodynamics formalism to nonequilibrium stationary state. The obtained results provide the possibility of predicting the liquid matter structural changes in the biological systems in the area influenced by the heavy ion beams.
